Q&A: Worries outweigh radiation threats in U.S.

All that worrying might cause more harm than the radiation from the Japan nuclear accident, experts say. A look at some common concerns.

In Japan, a baby is checked for radiation exposure before entering an evacuation… (AP Photo / Kyodo News )

With reports that a radiation plume from the Fukushima Daiichi nuclear plant could reach Southern California as soon as Friday, worried citizens have been hoarding potassium iodide pills, wondering if it's OK to go outside and otherwise fretting over an invisible, and somewhat unpredictable, threat.

But all that worrying might cause more harm than the radiation itself, experts say. Here are some answers to common concerns.

How much radiation do scientists think will arrive here?

No one knows yet — but probably not a whole lot. It's unclear what's happening at the Japanese power plant, and whatever radiation escapes has to travel thousands of miles to reach U.S. shores. Over that distance, it will be greatly diluted, if it gets here at all.

In fact, the winds have been shifting, often blowing westward, back toward Japan, rather than toward the U.S., California officials said in a news conference Thursday. "We are not in Japan," said Dr. Jonathan Fielding, director of Public Health for Los Angeles County. "We are not within 10 miles of the reactor. We are 5,000 miles away — and we know a lot about dispersal patterns over that distance."

How much risk will any radiation that reaches here pose?

Not much. Gregory Jaczko, chairman of the Nuclear Regulatory Commission, an independent agency that regulates U.S. commercial nuclear power plants, told reporters Thursday that the basic science involved suggested that "there can't be any risk or harm to anyone here in the United States, or Hawaii, or any of the other [U.S.] territories."

Dr. Kei Iwamoto, of the faculty of the Division of Molecular and Cellular Oncology at UCLA, told The Times that he believed the amount of radiation from Japan that a person in California might be exposed to will be very low — perhaps around one microsievert.

To put that in perspective, people get some amount of radiation every day. Humans are exposed, on average, to 3,000 microsieverts of natural background radiation per year, according to the Centers for Disease Control and Prevention. One dental X-ray would add 40-150 µSv to that baseline. A CT scan of the abdomen, according to the Food and Drug Administration, would tack on another 8,000 µSv — more than 2 1/2 years of background radiation.

Did radiation reach here from Chernobyl? What happened then?

Yes, a tiny amount did reach the United States. But its health effects were miniscule, if they existed. "The radiation from the 1986 accident was negligible from a health standpoint. I know of no evidence that that accident caused any increase in cancer in this country," Iwamoto said.

What about kids? I've heard they're more sensitive to radiation.

That is true. "Kids are more vulnerable to radiation for a couple of reasons," said Dr. William Hendee, a radiation physicist with the Medical College of Wisconsin. "Their organs and tissues are growing and developing. Growing and developing cells are more susceptible to radiation. Kids also have a longer lifespan."

So should I keep them away from school?

No. Radiation levels are not likely to get very high. There is no reason to keep your kids out of school.

Should I take iodine tablets or eat iodized salt? It can't hurt, can it?

Well, yes, it can hurt. The tablets can be risky for some people — especially pregnant women. There is no reason to take iodine tablets at this point, said California officials at the news conference.

Indeed, potassium iodide is not recommended at all until radiation levels hit the tens of thousands of microsieverts. Levels won't reach anywhere approaching that level here.

In cases of true radiation exposure — for example, for people living close to the reactors in Japan — the benefits of potassium iodide outweigh the risks. The tablets can protect the thyroid from exposure to radioactive iodine-131 by "filling up" the gland and preventing it from taking up the radioactive iodine.

But potassium iodide can be harmful to people who are allergic to the substance or who have the skin disorders dermatitis herpetiformis or urticaria vasculitis, according to the Centers for Disease Control and Prevention. Pregnant women and infants should not be given potassium iodide because it could cause a serious thyroid disorder in infants. The supplements can cause some side effects including nausea, rashes and inflammation of the salivary glands.

As for eating iodized table salt to ward off the effects of radiation, that might work, but you'd have to gobble a great deal of the stuff — 3 1/2 pounds a day, according to the Salt Institute, an industry group — to reach the 130 milligrams of iodine you'd need. Even the institute said, in a statement, that this was not a good primary defense against radioactive fallout. That's saying something. Don't do it.